Instead of hardcoded "QGroundContorl" strings

Should be all working now except for distance < radius cases.

This makes VehicleComponents reusable from core plugin without
requiring override of prerequisiteSetup

Not the other way around

Plus remove unused code

- Look backwards from insert point
- Only pull altitude from _WAYPOINT items
- Only set altitude on _WAYPOINT items

* Holds all the settings for the app
* Allows core plugin to override default values